In disc storage devices, programmable data is stored as bits in circular tracks on rigid or flexible discs. In order to access the stored data, a read/write disc head scans the circular tracks of the storage disc and converts the magnetic codes recorded on the surface of the disc into electric code signals as the disc is rotated about a shaft at relatively high speeds by a disc drive motor. In operation, the read/write head must be positioned accurately relative to the particular track which is being inscribed or read because an error in the position of the head could alter or, in extreme cases, permanently damage the stored program or data. Accordingly, the disc speed must be controlled to accommodate movement of the read/write head.
Typically, disc speed is controlled by drive electronics and speed control circuits which electromagnetically communicate with a disc drive motor. More particularly, drive electronics and speed control circuitry are etched or soldered onto printed circuit boards or the like, and connector circuitry, such as hard wires, couple the printed circuit boards to the disc drive motor to transmit electronic control signals between the printed circuitry and the disc drive motor.
In the past, disc storage devices have included wire connectors coupled to printed circuit boards which carry signals from circuit components for controlling and regulating the driving motor, as will now be described below in association with FIG. 1. There will be seen a conventional disc storage drive 10 including a stationary shaft 12, a hub 14 rotatably mounted about the shaft by bearings 16 and 18, and a magnetically active stator, generally designated 20, including stator stack 22 and stator windings 24. An annular rotor magnet 26 is shown mounted on an inner surface 28 of hub 14 to magnetically interact with the magnetic parts of the stator.
Speed control circuitry and other drive electronics are coupled to the disc drive motor through stator winding connections 30 which are channeled through stationary shaft 12. The winding connections 30 may be soldered or otherwise coupled to the stator windings 24 as shown at 32. At an opposite end, winding connections 30 are connected to printed circuitry which controls the amount of current supplied to the stator windings, and therefore controls the speed and operation of the drive motor.
Although such connections facilitate transfer of current from external circuitry to the stator windings of the disc drive motor, soldering the connecting wires to the stator and external circuitry is a labor intensive assembly process since all such connections must be reliable and exact. Moreover, confining the connecting wiring within the shaft results in a design having poor field serviceability. Further, external connecting wires are undesirable in view of the current trend towards high density circuitry.
Another problem encountered in prior disc drive devices occurs when contaminant particles, such as lubricant and/or metal particles produced by the rotation of the bearings, escape from the interior of the motor to the "clean environment" disc storage area of the drive The contaminant particles may cause operational difficulties or, more significantly, permanently damage the stored discs, heads and other sensitive drive elements Additionally, dust and dirt produced by the highly structured winding surface may also be detrimental to the operation of the disc drive device.
It has been realized in the past to include ferrofluidic seals in disc drive motors to prevent emanation of dust and dirt from the interior mechanical workings of the motor to the disc storage area. Ferrofluidic seals induce a sealing action between stationary and rotary parts of the disc drive motor by combining magnetic fields and lubricant emulsions containing magnetically conductive particles at the junction of the stationary and rotary parts.
Labyrinth seals have also been designed in past disc drive motor devices to significantly reduce, and in some cases completely prevent, the passage of contaminant particles from the internal parts of the disc drive motor to the area housing the storage discs The term "labyrinth seal" refers to an intricate, circuitous path or tight enclosure defined by the structure of the motor that inhibits the movement of particulate matter from the interior of the motor, as opposed to a complete closure such as produced by a ferrofluidic seal.
Although these disc drive designs utilizing ferrofluidic or labyrinth seals have effectively prevented contaminated particles from damaging stored discs, such designs require numerous parts to effectively construct the contaminant-proof seals, resulting in high manufacturing costs.
The difficulties suggested in the preceding are not intended to be exhaustive but rather are among many which tend to reduce the effectiveness of prior disc drive assemblies. Other noteworthy problems may also exist; however, t hose presented above should be sufficient to demonstrate that such disc drive assemblies appearing in the past will admit to worthwhile improvement. Accordingly, it is therefore a general object of the invention to provide a disc drive assembly which will obviate or minimize difficulties of the type previously described.
It is a specific object of the invention to provide a disc drive assembly which permits electronic communication between a printed circuit board and a stator of a disc drive motor.
It is another object of the invention to provide a disc drive assembly which eliminates external wiring and thereby reduces the number of components necessary for communication between a printed circuit board and a disc drive motor.
It is still another object of the invention to provide a disc drive assembly which reduces the risk of contaminant particles escaping from the disc drive motor into the "clean environment" disc storage area.
It is a further object of the invention to provide a disc drive assembly which is easily assembled, compact, easily serviceable, and economical to manufacture.